Unplug the refrigerator and open the door.
Remove the screws holding the refrigerator door handle in place, if applicable, and remove the handle.
Pry the rubber lining of the refrigerator door up with your putty knife. This will expose the screws holding the lining in place.
Remove the screws holding the lining in place and remove the lining.
Slide the filler board out of the refrigerator door to expose the panel.
Slide the panel out of the door and replace with a new one that fits your particular model refrigerator.
Reinstall the filler board, lining, screws and door handle.